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Uma G.,National Central University | Uma G.,Koneru Lakshmaiah University | Liu J.Y.,National Central University | Chen S.P.,National Central University | And 3 more authors.
Earth, Planets and Space | Year: 2012

The latest version of the International Reference Ionosphere (IRI-2007) model includes an option for spread-F occurrence prediction for the first-time. The IRI-2007 spread-F occurrence is a function of solar 10.7 cm radiation flux, F10.7. In this paper, an attempt is made to cross-examine the spread-F occurrence derived by the IRI-2007 and the ionospheric scintillations in terms of the maximum value of the S4 index (S4max) between 150-350-km altitudes, calculated from fluctuations of the signal-to-noise ratio (SNR) intensity in the L1 channel of GPS radio occultation signals using FORMOSAT-3/COSMIC (F3/C) satellites during the low solar activity years 2007-2009. It is found that S4max maintains a fairly good consistency with spread-F occurrence simulated by IRI-2007 in the Brazilian region. Thus, the global S4 index statistics can be considered as a viable source of database to be incorporated into the global IRI spread-F prediction scheme owing to fact that the F3/C satellites can provide an unprecedented global database including the S4 index. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS).


Meerja K.A.,Koneru Lakshmaiah University | Ho P.-H.,University of Waterloo | Wu B.,Tianjin University | Yu H.-F.,National Taipei University of Education
Computer Networks | Year: 2013

Femtocell networks are widely deployed to extend cellular network coverage into indoor environments such as large office spaces and homes. Cognitive radio functionality can be implemented in femtocell networks based on an overlay mechanism under the assumption of a hierarchical access scenario. This study introduces a novel femtocell network architecture, that is characterized by a completely autonomous femtocell bandwidth access and a distributed media access control protocol for supporting data and real-time traffic. The detailed description of the architecture and media access protocol is presented. Furthermore, in-depth theoretical analysis is performed on the proposed media access protocol using discrete-time Markov chain modeling to validate the effectiveness of the proposed protocol and architecture. © 2013 Elsevier B.V. All rights reserved.


Vasavi C.,Koneru Lakshmaiah University | Suresh Kumar G.,Koneru Lakshmaiah University | Murty M.S.N.,Sainivas
Soft Computing | Year: 2016

This paper deals with the fuzzy set-valued functions of real variables on time scale whose values are normal, convex, upper semicontinuous and compactly supported fuzzy sets in (Formula presented.). We introduce and study the fundamental properties of new class of derivative called generalized delta derivative ((Formula presented.) -derivative) and generalized delta integral ((Formula presented.) -integral) for such fuzzy functions. © 2014, Springer-Verlag Berlin Heidelberg.


Madhavi Latha D.,Koneru Lakshmaiah University | Madhav B.T.P.,Koneru Lakshmaiah University | Datta Prasad P.V.,Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah University
Journal of Molecular Liquids | Year: 2010

Different thermodynamic parameters such as Sharma parameter (S o), Huggins parameter (F), reduced volume (V∼), reduced compressibility (V∼ C1) etc., are estimated from the volume expansion coefficient (α) for N-(p-n-alkoxybenzylidene)-p-n- pentyloxy aniline (nO.O5) compounds in isotropic and liquid crystalline phases. The parameters like intermolecular free length (Lf) and molecular radius (mr) are also computed from density and refractive index for these nO.O5 compounds. The results are discussed in the light of these parameter variations with temperature in a particular phase, in a liquid crystal molecule and in a homologous series. The thermodynamic parameter So exhibits a constant characteristic value (1.15 ± 0.05) in all the compounds like other reported liquid crystalline compounds and liquids. The variation of other thermodynamic parameters in all the phases of these compounds with temperature is discussed in the light the body of the data available. © 2010 Elsevier B.V. All rights reserved.


Ramakrishna M.,Hindu College | Rao N.,Hindu College | Prasad P.V.D.,Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah University
Molecular Crystals and Liquid Crystals | Year: 2010

Alkoxy benzoic acids are well-known liquid-crystalline compounds with nematic phase of long thermal ranges. The refractive indices measurements are carried out using a wedge-shaped cell with the help of a modified spectrometer. The birefringence (δn=ne-no) is obtained directly by using the method developed by Kuczynski et al. [10] in all the available compounds (alkoxy chain number n=3 to 12 and 16). The higher homologues exhibit the smectic-C phase along the nematic phase. The molecular polarizabilities are calculated from the refractive indices and the density using the well-known internal field models. The molecular anisotropy is estimated from the Lippincott -function model and molecular vibration method. The order parameter, S, is estimated (a) using molecular polarizabilities and the molecular anisotropy for both the models, (b) from Haller's extrapolation using molecular polarizabilities, and (c) directly from the birefringence, a method developed by Kuczynski et al. [10] along with the nematic phase. Further, the order parameter from n, without the consideration of any internal field model, to the nematic molecule is compared with S obtained from density due to Maier et al. [23]. The results are compared with one another and the advantages and disadvantages are discussed. Copyright © Taylor & Francis Group, LLC.


Raghunath S.,G Narayanamma Institute of Technology and Science | Venkata Ratnam D.,Koneru Lakshmaiah University
Indian Journal of Radio and Space Physics | Year: 2016

Standalone Global Navigation Satellite System (GNSS) is inadequate for precise navigation of aircrafts. Ground-based Augmentation System (GBAS) augments the performance of GNSS for civil aviation by providing differential corrections to the position of an aircraft during takeoff and landing. Ionospheric gradients affect the accuracy of GNSS and they can be detected and characterized from GNSS observations. In this paper, the ionospheric temporal and spatial gradients have been detected and the ionospheric drift velocity has been evaluated from the data recorded by GNSS receivers located at Koneru Lakshmaiah University, Guntur (GNT) and Indian Meteorological Department, Machilipatnam (MPM), Andhra Pradesh, India. Both the stations are chosen as they are situated close to each other and to the Vijayawada Airport. The rate of TEC index (ROTI) and numerical differentiation are applied to detect the ionospheric temporal gradients. Time-step and Stationpair methods are used to detect the spatial gradients. Ionospheric gradients at GNT and MPM stations for the month of January 2015 have been discussed. The gradients are found to have occurred mostly between 2000 and 2200 hrs LT. The maximum value of ionospheric gradient velocity is 473.25 ms-1. The S4 value is above 0.8 and the phase scintillation value is above 0.7 radians.


PubMed | National Institute of Technology Warangal, Bhavans College andheri W and Koneru Lakshmaiah University
Type: Journal Article | Journal: Journal of chemical biology | Year: 2016

2-Phenyl-1H-indole-3-carbaldehyde-based barbituric acid, thiobarbituric acid, thiosemicarbazide, isoniazid, and malononitrile derivatives were synthesized under photochemical conditions. The antitumor activities of the synthesized compounds were evaluated on three different human cancer cell lines representing prostate cancer cell line DU145, Dwivedi (DWD) cancer cell lines, and breast cancer cell line MCF7. All the screened compounds possessed moderate anticancer activity, and out of all the screened compounds, 5-{1[2-(4-chloro-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2b) and 5-{1[2-(4-methoxy-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2d) exhibited marked antitumor activity against used cell lines. Additionally, barbituric acid derivatives were selective to inhibit cell line DWD and breast cancer cell lines.


Suresh Kumar J.,Sri Venkateswara University | Pavani K.,Sri Venkateswara University | Sasikala T.,Sri Venkateswara University | Sreenivasa Rao A.,Koneru Lakshmaiah University | And 3 more authors.
Solid State Sciences | Year: 2011

The present paper describes the optical absorption, photoluminescence and lifetime measurements of trivalent samarium doped calcium fluoroborate (CFB) glasses. From the observed energy levels, the free-ion energy level parameters for the 4f5 electronic configuration of Sm3+ ion have been evaluated using HFI model. The experimental oscillator strengths of absorption bands have been analyzed to determine the Judd-Ofelt (J-O) parameters. From the evaluated J-O parameters and luminescence data, the radiative parameters such as AR, τR and σe values were obtained from the excited 4G 5/2 level to different lower energy levels. The decay curves of 4G5/2 → 6H7/2 transition were analyzed by the Inokuti-Hirayama model assuming dipole-dipole interaction between the dopant ions. The decrease of fluorescence intensities as well as measured lifetimes at higher concentrations has been explained based on energy transfer process through cross-relaxation between Sm3+ ions. © 2011 Elsevier Masson SAS. All rights reserved.


Patra S.,Koneru Lakshmaiah University
International Journal of Applied Engineering Research | Year: 2015

MANET is a wireless network connected using movable devices with unstable topology. Unlike MANETS, in a network with static topology, one can estimate and detect the cause for any disturbance in the network. The dynamic topologies in a MANET and the absence of central supervision make the transmission completely prone to several hits. The Mobile Adhoc network is wireless, very adaptive and supports the nodes to travel. This feature is a major support in many applications, but generates many security flaws. This paper discusses various terms related to security in an alphabetical order and references are stated to deal with the each attack. This may serve as a mini dictionary for attacks in Mobile Adhoc networks. © Research India Publications.


Vasavi C.,Koneru Lakshmaiah University | Suresh Kumar G.,Koneru Lakshmaiah University | Murty M.S.N.,Sainivas D. No. 21 47
Journal of Uncertain Systems | Year: 2016

Using the concept of Hukuhara difference, in this paper we introduce a class of new derivatives called Hukuhara delta derivative and a class of new integrals called Hukuhara delta integral for fuzzy set-valued functions on time scales. Moreover, some corresponding properties of Hukuhara delta derivative and Hukuhara delta integral are discussed. Furthermore, sufficient conditions are established for the existence and uniqueness of solution to the fuzzy dynamic equations on time scales with the help of Banach contraction principle. © 2016 World Academic Press, UK. All rights reserved.

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